In a monsoon area, the wet and highly changeable climate causes an article to be dampened and damaged easily, suffering mildew, discoloration, off-flavor, etc. For this reason, a storage bag with three sealed faces and one opened face is commonly used for storing or packing an article. A user must still use their hands to squeeze air out of the storage bag and then seal the storage bag after packing an article in it n order to ensure the stored object is damp-proof.
A storage bag in common use places an exhaust passageway on one side of the bag, one end including an air inlet and another end including an air outlet. When the user squeezes the bag with their hands, air flows from the air inlet into the exhaust passageway, passes through the exhaust passageway and is then expelled out of the air outlet. Examples of such bags are Chinese Patent Application No. 01144648.X entitled “compressing storage bag”, U.S. Pat. No. 6,116,781 entitled “storage bag with one-way air valve”, U.S. Pat. No. 6,357,915 entitled “storage bag with one-way air valve” and U.S. Pat. No. 6,729,473 entitled “air-evacuable bag with double-layered valve film and method for manufacturing same”. However, bags of this design are very time and labor consuming; air exhaust is unable to be processed and the air exhaust effect is not good if the air outlet is blocked by an article; air is liable to stay in the side areas of the air exhaust passageway and is unable to be expelled. Moreover, the air outlet must be large enough to allow air to be expelled, or it will cause air to flow back to the storage bag along the air exhaust passageway. In addition, the shared air exhaust passageway is unable to stop air from flowing back such that air sealing is insufficient, so that it is not possible to achieve smooth air expulsion and long air locking time after the air has been expelled.